phd – Cosmology with Galaxy Clustering
Requisits: Diploma in Physics

University of Potsdam, Germany
Descripció: One of the fundamental goals of Cosmology is to understand how the Universe evolved from initial density fluctuations to the large-scale structure of galaxies which is observed today as the cosmic web. Cosmological models can predict the properties of this structure for a given decomposition of the universal energy into matter and the acceleration of the cosmic expansion. While the major part of matter is believed to consist of an unknown and invisible type of particles, the observed galaxies are assumed to be biased tracers of the total matter distribution. A detailed understanding of galaxy bias is necessary for constraining cosmological models by comparing their predictions to observations.

In this thesis galaxy bias will be studied using observational and simulated data. As a first step different methods for measuring the bias will be investigated. For this purpose the bias will be derived from the MICE Simulation and the Millennium Simulation using two- and three-point correlation functions. This results will be compared to direct determinations of the bias from the density contrast. The analysis will be performed for different scales, mass ranges and redshifts. Furthermore the three-point correlation function will be used to test the local model for bias. Deviations of the measurements from the local model predictions will be studied for different cluster shapes.

As a second step the dependence of galaxy bias on galaxy properties such as spectral type, color, morphology, magnitude and spatial environment will be investigated. For this purpose mock galaxy catalogs will be used, including semi-analytic models that are imposed on the Millennium Simulation and halo occupation models from the MICE simulation. The properties of the mock galaxies will be compared to observational data such as PAU and SDSS.

These studies will provide a base for further investigations of galaxy bias derived from weak lensing observables and redshift space distortions.

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Generalitat de CatalunyaUniversitat de BarcelonaUniversitat Autònoma de BarcelonaUniversitat Politècnica de CatalunyaConsejo Superior de Investigaciones CientíficasCentres de Recerca de Catalunya